Relays and circuit breakers are known devices that contain electrical contacts, switching contacts, that are normally spaced apart and are thereby electrically isolated from one another by the ambient air or other insulating environment, but which may be moved into contact to provide direct electrical contact. In application those switching contacts are wired into electric circuits, so that the circuit is completed when the relay or circuit breaker is operated. When a relay or electric circuit breaker, closes, its switching contacts are moved into direct physical contact with one another, completing a current conducting path in such electric circuit. Electric current flows through the contacts in that electric circuit between the power source and the load. When the relay or breaker opens, the contacts move and separate, interrupting the electrical current.
Initially, one expects that the physical separation of the contacts immediately interrupts the current as intended. However, under some circumstances an electric arc occurs between those contacts. As example, when the electrical potential between the relay's contacts is sufficiently high and the contact spacing very small, as is the situation when the contacts commence separation, the potential difference breaks down the air and bridges the small space or gap between the contacts, drawing the arc, which thereby allows continuance of some level of current through the contacts, and, hence through the electric circuit.
In most applications, the arc is almost indiscernible, insignificant and/or quickly extinguishes. In other applications such as those involving inductive loads or high voltages and high currents, arcing is significant. As is known, energy released by the arc pits and slowly destroys the switching contacts.
In the past, various means have been used to extinguish those unwanted arcs. One such means for relays and circuit breakers was to incorporate an inductive "blow out coil". The coil creates a magnetic field that immerses the arc. Through interaction with the magnetic field, the familiar ev X B relationship described in the physics literature, the arc lengthens and moves out in a kind of motor action that is familiar to those skilled in the art.
Electric arcs also sometimes occur in electron tubes or vacuum tubes, as variously termed, especially in high power electron tubes. In electron tube operation high voltages are applied between metal elements, electrodes. Those electrodes, such as the tube's plate and cathode electrodes, are spaced apart in a vacuum environment in which they are housed. Should the applied voltage temporarily exceed the breakdown potential between two elements, an arc over occurs. Sometimes an arc is caused by "whiskers" that grow on electrodes or by small amounts of gas released from the electrodes. A small arc may burn off a whisker, but can quickly destroy those elements, heating the elements to temperatures at which they melt or evaporate, which renders the tube inoperative.
As a general observation and with either device, if physical conditions are such that creation of an arc from time to time is unavoidable, the greater the duration of the arc, the greater damage the arc causes. Conversely, the shorter in duration of the arc, then less damage is experienced.
An object of the present invention therefore is to extinguish arcs more quickly than the prior protective devices, thereby minimizing damage. Indirectly, the present invention, thus, improves and lengthens the service lifetime of switching contacts in relays, circuit breakers and vacuum tubes, an ancillary object to the invention.
A further object of the invention is to provide an efficient arc suppressor that is smaller in size than and which can be produced at lesser cost than prior arc suppressors.